Until recent years, internal combustion engines have employed almost unchanging principles of operation. This applies to both two-cycle engines and four-cycle engines. However, as the problems of pollution control and efficiency are addressed, there have been new approaches to the functioning of these engines. For example, the shape of the combustion chambers has been modified, fuel injection is being used, and various devices have been devised to "preignite" the fuel mixture in localized spots in order to enhance the ignition of the total fuel mixture. Most automobile manufacturers, in the United States at least, utilize computer control which includes an adjustment of timing rather than rely upon vacuum control. Even multiple spark plugs for each cylinder are utilized in certain engines. Some engines are now manufactured with three or four valves per cylinder, rather than two, to improve performance. Some late model and experimental engines use various designs of piston and cylinder heads to form varying-shaped combustion chambers such as hemispherical, wedge, "L" and others. Still other engines utilize port, slide, poppet or rotary valves. These are just a few of the variations that have been utilized to improve engine efficiency and reduce the pollution caused by these engines.
Because of the many variations in engine design, certain definitions are used hereinafter with regard to application of the present invention to those engines. For example, reference will be made to the "exhaust", "exhaust manifold" or "hotside" to indicate the region of highest temperature in the combustion chamber, and "intake" or "intake manifold" to indicate the lowest temperature region.
Many of the improvements devised for internal combustion engines have originated in Japan, particularly for use in Honda and Toyota vehicles. Typical of such devices are shown in U.S. Pat. Nos. 4,038,959; 4,076,000; 4,092,969; 4,144,848; and 4,174,679. Other devices for this purpose are shown in U.S. Pat. No. 4,416,228 (for a German development), and a paper on "Swirl-Chamber Spark Plugs Improve Combustion Process", written about developments by Bosch engineers in Germany. Another special unit for increasing the efficiency of combustion is shown and described in U.S. Pat. No. 4,534,327, assigned to Bosch.
Also a device for these purposes is described in my U.S. Pat. No. 4,218,993. In the last of these references, I describe the use of the injection of a small quantity of highly combustible fuel into the region near the spark gap to enhance the ignition of the regular fuel mixture and to produce a high-speed flame to further ignite all of the fuel mixture.
Many of the devices require a substantial change in the structural portions of an engine and therefore are not of value in the conversion (i.e., retrofit) of a "conventional" engine. Of course, the structural changes required to accommodate these designs in a retrofit process will be determined by the specific engine design. The ignition devices of the prior art that can be used to retrofit an engine without structural change do not include elements for controlling the timing for satisfactory performance at speeds from idle to full throttle. They do little, if anything to eliminate combustion knock or enhance overall combustion control.
Although many of the devices that have been recently developed and put into service have improved efficiency, performance and reduced pollution, there is need for a further improvement for vehicles of the future. In 1983, a report (DOE/NASA/0131-1) prepared as a result of a joint study by the Department of Energy, the National Aeronautics and Space Administration, and the National Science Foundation stated "The concept that a lean combustion engine offers distinct advantages, both with respect to pollution as well as efficiency, is well known as attested by the development of stratified charge engines. However, efforts to achieve satisfactory performance under extra-lean conditions have been so far unsuccessful." Sandia National Laboratories, in a newsletter (Vol. 20, No. 4, Apr. 1985), reported on their research related to understanding "engine knock" in order to determine possible ways to prevent the same so that higher compression ratios can be used to increase fuel mileage and torque.
Accordingly, it is a principal object to provide a device for use in internal combustion engines, which will improve efficiency and performance, and will further reduce the generation of polluting emissions.
Another object of this invention is to provide means whereby extra lean fuel mixtures and/or low octane fuel can be used in an engine without producing combustion knock.
It is a further object of the present invention to provide a device to accomplish these advantages and which can be easily added to engines presently in service.
It is also an object of the present invention to provide a device that can be adapted to new production-type engines without major retooling.
It is another object to provide a device for this usage that accomplishes good performance at all power levels with little or no use of a conventional spark advance.
Another object of the present invention to provide a device with controlled flame delay which will allow it to be used in conventional engines with no timing adjustment or other alterations.
Still another object of this invention is to provide a device that will allow automobile and other manufacturers to reduce engine size while maintaining the same or greater power output, or to achieve higher output with the same size engine.
These and other objects of the present invention will become apparent upon a consideration of the drawings illustrated below and a complete description of the invention.